Difference between adaptive thresholding and normal thresholding in opencv
I have this gray video stream:
The histogram of this image:
The thresholded image by :
threshold( image, image, 150, 255, CV_THRESH_BINARY );
i get :
Which i expect.
When i do adaptive thresholding with :
adaptiveThreshold(image, image,255,ADAPTIVE_THRESH_GAUSSIAN_C, CV_THRESH_BINARY,15,-5);
i get :
Which looks like edge detection and not thresholding. What i expected was black and white areas . So my question is, why does this look like edge detection and not thresholding.
thx in advance
Adaptive Threshold works like this:
The function transforms a grayscale image to a binary image according to the formulas:
where T(x,y) is a threshold calculated individually for each pixel.
Threshold works differently:
The function applies fixed-level thresholding to a single-channel array.
So it sounds like adaptiveThreshold calculates a threshold pixel-by-pixel, whereas threshold calculates it for the whole image -- it measures the whole image by one ruler, whereas the other makes a new "ruler" for each pixel.